Astronomers have observed a rapidly circulating bubble of gas in the center of our galaxy.

This observation could help understand the behavior of black holes. The phenomenon would be of magnetic origin, according to the authors of the study that reveals the detection of this bubble.

Astronomers have observed the fleeting appearance of a bubble of gas that circulates at “mind-boggling” speeds around the black hole at the center of our galaxy, according to a scientific study published on Thursday.

The detection of this bubble, whose lifetime did not exceed a few hours, could provide information on the behavior of black holes. These astronomical objects are all the more mysterious in that they are literally invisible, since their gravitational pull is such that not even light can escape.

Sagittarius A*, the supermassive black hole lurking at the heart of the Milky Way, is about 27,000 light-years from Earth. It was detected thanks to the movement of the stars that orbited around it. The EHT collaboration, a global network of radio telescopes, published last May the first image of the ring of material that surrounds the black hole before being absorbed by it.

The image of a supermassive black hole at the heart of our galaxy, published on May 12, 2022.
The image of a supermassive black hole at the heart of our galaxy, published on May 12, 2022. © EHT COLLABORATION

A “very surprising” sign

ALMA, one of these radio telescopes located in Chile, has captured a “very surprising” signal in the observation data of Sagittarius A*, astrophysicist Maciek Wielgus, from the German Max Planck Institute for Radio Astronomy, explained to AFP.

Minutes before ALMA collected these data, the Chandra space telescope detected “a huge emission” of X-rays from Sagittarius A*, he explained.

This burst of energy, thought to be similar to solar storms on the Sun, sent a bubble of gas flying around the black hole at full speed, according to the study published in the journal Astronomy and Astrophysics.

The phenomenon observed for about an hour and a half made it possible to calculate that the gas bubble made a complete orbit of the black hole in just 70 minutes, and therefore at a speed equivalent to 30% of that of light, which amounts to 300,000 km per hour. second A speed that “defies the imagination”, according to Maciek Wielgus.

A phenomenon of magnetic origin.

The phenomenon would be of magnetic origin, according to a theory put forward by the scientist. The black hole’s magnetic field is so powerful that it prevents some of the matter that circulates around it from being absorbed by it.

But this accumulation of material gives rise to a “flux eruption”, which opens a gap in the magnetic field and releases a burst of energy, in the form of a gas bubble, according to the astrophysicist.

Observations of these magnetic fields should help us understand how black holes work. They could also indicate how fast these black holes are spinning.

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